gles2: only build tests when building SDL3 or when the headers are available

test/CMakeLists.txt

@@ -363,8 +363,11 @@ add_sdl_test_executable(testgles SOURCES testgles.c)
 if(ANDROID)
     target_link_libraries(testgles PRIVATE GLESv1_CM)
 endif()
-add_sdl_test_executable(testgles2 SOURCES testgles2.c)
-add_sdl_test_executable(testgles2_sdf NEEDS_RESOURCES TESTUTILS SOURCES testgles2_sdf.c)
+check_include_file("GLES2/gl2platform.h" HAVE_GLES2_GL2PLATFORM_H)
+if(HAVE_GLES2_GL2PLATFORM_H OR (TARGET SDL3-static OR SDL3-shared))
+    add_sdl_test_executable(testgles2 SOURCES testgles2.c)
+    add_sdl_test_executable(testgles2_sdf NEEDS_RESOURCES TESTUTILS SOURCES testgles2_sdf.c)
+endif()
 add_sdl_test_executable(testhaptic SOURCES testhaptic.c)
 add_sdl_test_executable(testhotplug SOURCES testhotplug.c)
 add_sdl_test_executable(testpen SOURCES testpen.c)